Beware the Killer Sudoku

Just when you thought the newspaper phenomenon of filling in 81 numbers in a box - otherwise known as Sudoku - couldn't get any bigger, along comes the next generation: Killer Sudoku.

No, it's not the name of the latest episode of Midsomer Murders - watch out, he's got a ballpoint pen! - but a new twist on the worldwide puzzle craze published for the first time today in the Times.

It is sure to spark off a new bout of Sudoku envy between rival newspapers, who have bickered over who came up with the idea first, and whose Sudokus are bigger, better - and most complicated.

The Times claims Killer Sudoku is its most fiendish incarnation yet. As well as every row, every column, and every 3x3 box having to feature the numbers one to nine, Killer Sudoku features oddly shaped "inner boxes", each of which must add up to the small number written in the top corner of that box. Confused? You will be.

The new puzzle has been created by Tetsuya Nishio, whom the Times describes as the "undisputed grand master of Sudoku". Called Samunamupure, it translates as "sum number place", but the Times has gone for the rather catchier Killer Suduko.

"This new variation will be a dreadful challenge to you," says Nishio. "Do not get too addicted. We can make these puzzles so difficult that it would take a champion six hours to complete one." Commuters who enjoy filling in the puzzles on their way to work are going to have to move further away from their workplace. We suggest New York.